JP2000265067A - Addition-curable silicone rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an addition-curable silicone rubber composition having a good storage stability and a rapid curability by compounding an organopolysiloxane having Si-bonded alkenyl groups, an organohydrogenpolysiloxane having Si-bonded hydrogen atoms, a platinum catalyst, and a (meth)acrylic ester having a specified m.p. SOLUTION: This composition contains an organopolysiloxane represented by the composition formula: R1aR2bSiO(4-a-b)/2 and having at least two Si-bonded alkenyl groups, an organohydrogenpolysiloxane represented by the composition formula: R3cHdSiO(4-c-d)/2 and having at least two Si-bonded hydrogen atoms, a platinum catalyst, and a (meth)acrylic ester having an m.p. of 40 deg.C or higher. In the formulas, R1 is a (substituted) monovalent hydrocarbon group having no aliphatic unsaturation; R2 is an alkenyl; a is 0.96-2.00; b is 0.0001-0.5; a+b is 1.90-2.04; R3 means the same as R1; c is 0.70-2.0; d is 0.005-1.0; and c+d is 0.8-3.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-part or two-part addition-curable silicone rubber composition having sufficient storage stability and rapid curability.

[0002]

2. Description of the Related Art Addition-curable silicone rubber compositions using platinum or a platinum compound as a curing catalyst are excellent in curability and can be applied to both millable and liquid types as materials. Used in Particularly, the liquid type is useful as an adhesive, a molding material, a LIMS material, and the like. Both types mix the composition and / or
Alternatively, by heating, a crosslinking reaction is promoted, and a cured rubber product can be obtained.

[0003] In the case of the one-pack type, a curing control agent (ie, a hydrosilylation reaction control agent) is usually blended in order to ensure the preservability (preservation time before use) of the composition. Curing requires heating. in this case,
High-temperature heating is desirable for accelerating the curing, but if high-temperature heating is not possible for some reason, heating at low temperature must be performed for a long time. When heating for a long time is inconvenient, the two-liquid type must be used. Therefore, it is desired that the one-pack type has sufficient storage stability and can be cured in a short time even at a low temperature. In the case of the two-pack type, it is desirable to have sufficient storage stability and to be able to cure at a low temperature in a short time.

Therefore, various studies have hitherto been made on both types to obtain a curable composition having a sufficient balance between sufficient storage stability and rapid curability. In particular, for the one-pack type, various studies have been made using a vinyl-containing siloxane, a phosphorus compound, a nitrogen compound, acetylene alcohol and the like as a curing control agent.

[0005]

However, an addition-curable silicone rubber composition having a sufficient balance between sufficient storage stability and rapid curability in both the one-pack type and the two-pack type has not yet been obtained. Absent. Accordingly, an object of the present invention is to provide an addition-curable silicone rubber composition having a sufficient balance between sufficient storage stability and rapid curability.

[0006]

According to the present invention, there are provided means for achieving the above object: (A) average composition formula (1): R ¹ _a R ² _b SiO
_{(4-ab) / 2} (wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, R ² represents an alkenyl group, and a represents a number of 0.96-2.00. And b is 0.0001-
0.5 and a and b are a + b = 1.90 to 2.04
To be satisfied. An organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule represented by the following formula (B): (B) average composition formula (2): R ³ _c H _d SiO _{(4-cd) / 2} ( In the formula, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, c is a number from 0.70 to 2.0,
d is a number from 0.005 to 1.0, and c and d are c + d = 0.
Satisfies 8 to 3.0. A) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule, (C) a platinum-based catalyst, and (D) a (meth) acryl having a melting point of 40 ° C. or more. Provided is an addition-curable silicone rubber composition comprising an acid ester compound.

The composition of the present invention may further contain, if necessary, (E) an acetylene alcohol compound or a compound in which the alcoholic hydroxyl group (C-OH) of the compound is modified with silane or siloxane.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. <(A) Organopolysiloxane> The organopolysiloxane of the component (A) is represented by the average composition formula (1): R ¹ _a R ² _b SiO _{(4-ab) / 2} At least two attached alkenyl groups
It is used as a base polymer.
The molecular structure of the organopolysiloxane is not particularly limited, and may be any of a linear, branched, cyclic, or three-dimensional network structure, and a polymer composed of a single siloxane unit or two or more types. May be a copolymer composed of siloxane units of the general formula (I), but usually, both ends of the molecular chain are blocked with triorganosiloxy groups, and the main chain is substantially composed of repeating diorganosiloxane units. It is generally an organopolysiloxane. The alkenyl group in the molecule may be bonded to either the silicon atom at the terminal of the molecular main chain or the silicon atom in the middle of the molecular chain, or may be bonded to both of them. In view of the properties and the like of the above, it is preferable that the compound contains at least an alkenyl group bonded to silicon atoms at both ends of the molecular chain.

In the average compositional formula (1), R ¹ may be the same or different, and has 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and is substituted or unsubstituted without an aliphatic unsaturated bond. Represents a monovalent hydrocarbon group. Specific examples of R ¹ include:
Alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, octyl group and dodecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group; phenyl group, tolyl group and xylyl Aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group; and at least some of the hydrogen atoms of these hydrocarbon groups are fluorine atoms, bromine atoms, halogen atoms such as chlorine atoms A substituted hydrocarbon group substituted with a nitrile group and the like, for example, a trifluoropropyl group, a chloromethyl group, a cyanoethyl group and the like. Among these, all are preferably methyl groups from the viewpoint of ease of synthesis and chemical stability. If necessary for the characteristics, a part of the methyl group may be substituted with a phenyl group or a trifluoropropyl group.
R ² represents an alkenyl group. Specific examples of R ² include those usually having about 2 to 6 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a pentenyl group, a hexenyl group, and a cyclohexenyl group. However, a vinyl group and an allyl group are preferable, and a vinyl group is more preferable in view of easiness of synthesis and chemical stability. a is a number of 0.96 to 2.00, preferably 1.8 to 2.00, b is a number of 0.0001 to 0.5, preferably 0.001 to 0.1, and a and b are a + b = 1.90 to 2.04, preferably
Satisfies 1.95 to 2.02.

The viscosity of the organopolysiloxane at 25 ° C. is generally at least 10 cSt (centistokes), preferably 50 to 5,000,000 cSt, more preferably 50 to 5,000,000 cSt, in view of the flexibility of the obtained cured product and the workability of the composition. 100-1,000,0
It is in the range of 00cSt.

In place of the organopolysiloxane of component (A)
A typical example is methylvinylsiloxane cyclic polymerization.
Body, methylvinylsiloxane / dimethylsiloxane cyclic
Copolymer, both ends of molecular chain trimethylsiloxy group blocked
Tylsiloxane / methylvinylsiloxane copolymer,
Trimethylsiloxy group-blocked methyl vinyl poly at both ends
Siloxane, di-blocked trimethylsiloxy group at both ends of molecular chain
Methyl siloxane, methyl vinyl siloxane, methyl
Phenyl siloxane copolymer, dimethyl vinyl at both ends of molecular chain
Lucyloxy group-blocked dimethylpolysiloxane, both ends of molecular chain
Dimethylvinylsiloxy group-blocked methylvinylpolysilo
Xan, di-dimethylvinylsiloxy group-blocked di-terminal
Methylsiloxane / methylvinylsiloxane copolymer,
Dimethyl vinylsiloxy group-blocked dimethyl ester at both ends of molecular chain
Roxane / monomethylsiloxane copolymer, both ends of molecular chain
Dimethylvinylsiloxy-endblocked dimethylsiloxane
For both methylvinylsiloxane and methylphenylsiloxane
Polymer, molecular chain both ends methyldivinylsiloxy group blocked di
Methyl polysiloxane, trivinylsiloxy at both ends of molecular chain
Di-blocked dimethylpolysiloxane, formula: R¹ _ThreeSiO_1/2
(However, R¹Is R in the average composition formula (1)¹Same meaning as
Has a taste. The same applies hereinafter. ) And a siloxane unit represented by
Formula: R¹ _TwoR^TwoSiO_1/2(However, R^TwoIs the average composition formula (1)
R in^TwoHas the same meaning as The same applies hereinafter. )
Siloxane unit and formula: R¹ _TwoSiO_{2 / Two}Indicated by
Loxane unit and a small amount of formula: SiO_4/2Shiroki indicated by
An organopolysiloxane copolymer comprising a sun unit,
R¹ _ThreeSiO_1/2Unit and R¹ _TwoR^TwoSiO _1/2Unit and SiO_4/2
An organopolysiloxane copolymer comprising¹ _Two
R^TwoSiO_1/2Unit and R¹ _TwoSiO_2/2And a small amount of SiO_4/2single
And an organopolysiloxane copolymer comprising¹R^Two
SiO_2/2Units and small amount of R¹SiO_3/2Unit and / or R^Two
SiO_3/2Organopolysiloxane copolymer consisting of units
And the following structural formula:

[0012]

Embedded image And the like.
These alkenyl group-containing organopolysiloxanes,
One type may be used alone, or two or more types may be used in combination.

<(B) Organohydrogenpolysiloxane> The organohydrogenpolysiloxane of the component (B) has at least two, preferably at least three, hydrogen atoms bonded to silicon atoms in the molecule. Average composition formula (2): represented by R ³ _c H _d SiO _{(4-cd) / 2} , wherein a hydrogen atom (ie, SiH group) bonded to a silicon atom in the component (B) is a component described later. In the presence of the platinum-based catalyst (D), it functions as a cross-linking agent that gives a three-dimensional network structure by an addition reaction with an alkenyl group bonded to a silicon atom in the component (A). The molecular structure of the organohydrogenpolysiloxane is not particularly limited, and may be any of a linear, branched, cyclic, and three-dimensional network structure. For example, a polymer composed of only a siloxane unit having a SiH group, or a polymer having a SiH group, a triorganosiloxy unit, a diorganosiloxane unit, a monoorganosiloxane unit, and the formula: SiO _4/2 May be a copolymer with at least one selected from the group consisting of siloxane units. The degree of polymerization is not particularly limited, but is preferably from 3 to 300, particularly preferably from 4 to 150, from the viewpoint of compatibility with component (A) and ease of synthesis. .

In the average composition formula (2), R ³ may be the same or different, and has 1 to 12 carbon atoms, preferably about 1 to 8 carbon atoms, and is substituted or unsubstituted without an aliphatic unsaturated bond. Represents a monovalent hydrocarbon group. Specific examples of R ³ include:
Examples are the same as those exemplified for R ¹ in the average composition formula (1), and all are preferably methyl groups from the viewpoint of ease of synthesis and chemical stability. If necessary for the characteristics, a part of the methyl group may be substituted with a phenyl group or a trifluoropropyl group. c is a number from 0.70 to 2.0, preferably 0.9 to 2.0, d is a number from 0.005 to 1.0, preferably 0.01 to 1.0, and c and d are c + d = 0.8 to
3.0, preferably 1.0 to 2.5 is satisfied.

Representative examples of the organohydrogenpolysiloxane of the component (B) include a methylhydrogensiloxane cyclic polymer, a methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, and trimethylsiloxy at both ends of the molecular chain. Group-blocked methyl hydrogen polysiloxane, molecular chain terminal trimethylsiloxy group-blocked dimethylsiloxane / methyl hydrogen siloxane copolymer, molecular chain terminal dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, molecular chain terminal dimethylhydrogensiloxy group Blocked dimethylsiloxane / methylhydrogensiloxane copolymer, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane / diphenylsiloxane at both molecular chains Polymer, dimethylhydrogensiloxy-group-blocked dimethylsiloxane / diphenylsiloxane copolymer, molecular-chain-end dimethylhydrogensiloxy-group, methylhydrogensiloxane-diphenylsiloxane copolymer, molecular-chain-end dimethylhydrogensiloxy, trimethylsiloxy-group Blocked methyl hydrogen siloxane / diphenyl siloxane copolymer, methyl hydrogen siloxane blocked with trimethylsiloxy group at both molecular chain terminals
Diphenylsiloxane / dimethylsiloxane copolymer,
Copolymer of (CH ₃ ) ₂ HSiO _1/2 unit and SiO _4/2 unit, (CH ₃ ) ₃ SiO _1/2 unit and (CH ₃ ) ₂ HS
a copolymer composed of iO _1/2 units and SiO _4/2 units, (C
H ₃ ) ₂ HSiO _1/2 unit, SiO _4/2 unit and (C ₆ H ₅ ) S
copolymers comprising iO _3/2 units, (CH ₃₎ HSiO
_2/2 units and (CH ₃ ) SiO _3/2 units and / or HSiO
_A copolymer comprising _3/2 units, and the following structural formula:

[0016]

Embedded image And the like. The organohydrogenpolysiloxane of the component (B) can be used alone or in combination of two or more.

The compounding amount of the component (B) includes the alkenyl contained in the component (A), including the high-density organohydrogenpolysiloxane (organohydrogenpolysiloxane whose main chain consists only of repeating methylhydrogensiloxane units). The number of hydrogen atoms (SiH groups) bonded to the silicon atoms of the component (B) per one group, and the silicon present in the entire organohydrogenpolysiloxane when an organohydrogenpolysiloxane other than the component (B) is present The number of hydrogen atoms (SiH groups) bonded to the atoms is 0.4 to 10 from the viewpoint of the curability of the composition, the non-foaming property at the time of curing, the strength of the cured product, and the stability of the cured product over time.
The amount is preferably such that the number is 1.2 to 5.0.

<(C) Platinum Catalyst> The platinum catalyst of the component (C) comprises an organopolysiloxane containing an alkenyl group, ie, an unsaturated aliphatic group, of the component (A) and an organohydrogenpolysiloxane of the component (B). Any known catalyst can be used to promote the addition reaction with the catalyst. Specific examples include platinum black; chloroplatinic acid; alcohol-modified chloroplatinic acid; complexes of chloroplatinic acid with olefins, aldehydes, vinylsiloxanes, acetylene alcohols, and the like. The amount of the catalyst is an effective amount, and may be appropriately increased or decreased according to a desired curing speed.
It is usually in the range of 0.1 to 2,0 ppm, preferably 1 to 200 ppm, as platinum metal, based on the composition.

In consideration of the use of the composition, it may be necessary to avoid the inclusion of corrosive components. In that case, the platinum-based catalyst must also be free of chlorine ions, and the platinum-based catalyst is preferably a zero-valent platinum complex having 5 ppm or less of chloride ions. Specific examples of such a platinum complex include U.S. Patent 3,715,334, U.S. Patent 3,775,452, and U.S. Pat.
And complexes of platinum and vinylsiloxane described in 3,814,730 and the like.

<(D) (Meth) acrylate compound> In the present specification, the (meth) acrylate compound is used to mean an acrylate compound and a methacrylate compound. Of component (D)
(Meth) acrylate compound is a component necessary for imparting sufficient preservability and rapid curability to the composition of the present invention, preferably those having no organosiloxane structure in the molecule, More than 40 ℃, usually 40-180 ℃,
Preferably, those having a melting point of 60 to 150 ° C are used.

The inventor of the present invention combines the above components (A) to (C) with this (meth) acrylate compound (ie, an acrylate compound and / or a methacrylate compound; the same applies hereinafter). It has been found that the compound dissolves in the siloxane component by heating, and unexpectedly the activity of the platinum-based catalyst is increased to increase the curing rate of the composition. Moreover, since the (meth) acrylate compound has a melting point of 40 ° C. or higher and is not dissolved in the siloxane component at room temperature, the activity of the platinum-based catalyst is not increased, and the stability of the composition, ie, the storage stability, Is obtained. Thus, the composition of the present invention has a sufficient balance between sufficient storage stability and rapid curability. The (meth) acrylate compound exhibiting the above effects is not particularly limited as long as it has a melting point of 40 ° C. or higher,

[0022]

Embedded image Containing 1 to 4 aromatic rings (e.g., phenylene ring), particularly 1 to 2 aromatic rings, and containing an etheric oxygen atom, a silicon atom or a fluorine atom in the structure. Preferred are those having about 12 to 30 carbon atoms and a monovalent to tetravalent, preferably divalent hydrocarbon structure.
In particular, the following general formula (3):

[0023]

Embedded image (Wherein, R ⁴ represents a hydrogen atom or a methyl group, and X represents 1 to
At least one selected from the group consisting of an oxygen atom, a silicon atom and a fluorine atom in the structure containing four aromatic rings
6 to 30 carbon atoms, preferably 12 carbon atoms, which may contain
Represents a divalent hydrocarbon group of -20, and a represents an integer of 1-6, preferably an integer of 2-4. ). In addition, as a specific example of X in general formula (3), the aromatic ring illustrated above is mentioned. The following are specific examples of the (meth) acrylate compound.

[0024]

Embedded image

These (meth) acrylic ester compounds can be used alone or in combination of two or more. The compounding amount is usually 0.0001 to 100 parts by weight of the organopolysiloxane of the component (A).
It is 5 parts by weight, preferably 0.001 to 3 parts by weight, more preferably 0.01 to 1 part by weight.

<(E) Acetylene alcohol compound or derivative thereof> The composition of the present invention may optionally contain, as an optional component, the acetylene alcohol compound of the component (E) or a modified compound thereof with a silane or siloxane. it can. This component (E) functions as a curing control agent (a reaction inhibitor for a platinum-based catalyst).
It is particularly desirable to add it when long-term storage is required.

The acetylenic alcohol compound only needs to have an ethynyl group and a hydroxyl group in the same molecule, but it is preferable that the ethynyl group and the hydroxyl group be bonded to the same carbon atom. Specific examples thereof include the following compounds.

[0028]

Embedded image Further, the modified compound of the acetylene alcohol compound with silane or siloxane is a compound in which the hydroxyl group of acetylene alcohol is converted to a Si—O—C bond and bonded to the silane or siloxane portion. For example, the following compounds may be mentioned.

[0029]

Embedded image

The compounding amount of the component (E) is an effective amount for obtaining a desired storage stability. Specifically, it may be 0 to 3 parts by weight based on 100 parts by weight of the organopolysiloxane of the component (A),
It is usually 0.001 to 3 parts by weight, preferably 0.01 to 1 part by weight.

As the curing control agent, conventionally, in addition to the acetylene alcohol compound, a vinyl group-containing polysiloxane, triallyl isocyanurate, alkyl maleates, hydroperoxide, tetramethylethylenediamine, benzotriazole or a mixture thereof, and the like have been known. It is known that, among these curing control agents, the component (E) specified in the present invention, when used in combination with the component (D), exhibits sufficient storage stability and rapid curability in a well-balanced manner.

<Other optional components> In addition to the above components (A) to (E), the composition of the present invention further comprises a reinforcing silica filler such as fumed silica or precipitated silica; quartz powder, diatomaceous earth. Non-reinforcing fillers such as calcium and calcium carbonate; coloring agents such as inorganic pigments such as cobalt blue and organic dyes; heat resistance and flame retardancy such as cerium oxide, zinc carbonate, manganese carbonate, red iron oxide, titanium oxide and carbon black Additives such as enhancers can be blended in amounts that do not interfere with the effects of the present invention. For the purpose of imparting conductive stability, it is also possible to mix carbon black, graphite, or the like, which is powdery, whisker-like, or has a developed structure.

<Applications> The composition of the present invention is used for adhesives, molding agents, and the like used around electric and electronic parts and around on-vehicle parts.
It is useful as a material (such as LIMS) for molded silicone rubber.

[0034]

The following examples and comparative examples are given below, but the present invention is not limited to these examples. Me and Vi mean a methyl group and a vinyl group, respectively. [Examples 1 to 10, Comparative Examples 1 to 6] The following components were mixed in accordance with the formulations shown in Tables 1 and 2 to prepare one-part addition-curable silicone rubber compositions. And the curability was evaluated by the following test method. The results are also shown in Tables 1 and 2. Alkenyl group-containing organopolysiloxane V-Sx 1 Formula: ViMe ₂ Si—O — (— SiMe ₂ —O—) ₄₀₀ —SiMe ₂ Vi group-containing organopolysiloxane represented by Vi (viscosity at 25 ° C .: 5,
050cSt) V-Sx 2 Formula: ViMe ₂ Si-O-(-SiMe ₂ -O-) ₈₀₀ -(-SiMeVi-O-) ₁₂ -SiMe ₂
Vinyl-containing organopolysiloxane represented by Vi (25
Viscosity at ℃: 510,000 cSt) Organohydrogenpolysiloxane H-Sx Formula: Me ₃ Si-O-(-SiMe ₂ -O-) ₁₅ -(-SiMeH-O-) ₂₀ -Organo represented by -SiMe ₃ Hydrogen polysiloxane (viscosity at 25 ° C: 46 cSt) ・ Platinum catalyst Toluene solution of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum (containing 0.5% by weight as platinum metal)・ Curing control agent

[0035]

Embedded image ・ (Meth) acrylate compound

[0036]

Embedded image

<Test method> Storage test The composition was placed in a 100 ml closed glass bottle at 5 ° C or 25 ° C.
And the number of days until the value of the viscosity reaches twice the value immediately after preparation is obtained, and this is used as an index for the evaluation of storage stability.・ Curing test The composition is heated at 80 ° C or 100 ° C using a rheometer, and the time from the start of heating to the start of curing (T10)
Is measured.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

The addition-curable silicone rubber composition of the present invention has a good balance between good storage properties and rapid curability. Therefore, it is expected that workability will be high and will greatly contribute to improvement in productivity.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/5425 C08K 5/5425 C08L 83/05 C08L 83/05

Claims (3)

[Claims] (A) Average composition formula (1): R ¹ _a R ² _b SiO
_{(4-ab) / 2} (wherein, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, R ² represents an alkenyl group, and a represents a number of 0.96-2.00. And b is 0.0001-
0.5 and a and b are a + b = 1.90 to 2.04
To be satisfied. An organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule represented by the following formula (B): (B) average composition formula (2): R ³ _c H _d SiO _{(4-cd) / 2} ( In the formula, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, c is a number from 0.70 to 2.0,
d is a number from 0.005 to 1.0, and c and d are c + d = 0.
Satisfies 8 to 3.0. A) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule, (C) a platinum-based catalyst, and (D) a (meth) acryl having a melting point of 40 ° C. or more. An addition-curable silicone rubber composition containing an acid ester compound. 2. The addition-curable silicone rubber composition according to claim 1, further comprising (E) an acetylene alcohol compound or a compound in which the alcoholic hydroxyl group of the compound is modified with silane or siloxane. 3. A cured product obtained by curing the composition according to claim 1 or 2.